A homeless man went inside Montclair High School Friday morning and smoked a cigarette in the lobby of the auditorium, officials said.

The man was inside the building at 6:54 a.m. before school started and entered through an auditorium door that was open for teachers, Principal Anthony M. Grosso said in an email to parents Friday.

A student saw the man inside and called police and the main office. Security guards came to the area but the man was already leaving, Grosso stated.

"All doors are normally locked and moving forward, we will be especially diligent that all doors are kept locked unless a security guard is posted at the door," the principal said in the letter to parents.

"We will be meeting as an administrative and safety team to ensure that a situation like this does not occur again, and we will be proactive with all safety and security measures and all access points to the building."

Classes were not disrupted because of the intrusion.

Superintendent of Schools Dr. Kendra Johnson said that even though no one was hurt district officials are taking the incident "very seriously."

Johnson said officials have talked with security consultants about any recommendations about protocol and safety measures.

"Today’s incident reminds us, once again, to remind students to keep safety first and alert trusted adults and authorities if they see something," she stated in a letter to parents. "We recognize our obligation to ensure our students and staff feel safe on campus, and we are continuing to work with our safety teams and consultants to ensure this situation does not happen again anywhere in our district."